formula for logarithms to base two of a number

dynamo

Is there a formula for finding logarithms to base two of a number.If so wtat is it.Thanks for any replying.

Dormilich

you mean if you don't have a calculator at hand that computes the logarithms?

there are some series you can use.

JosAH

There's a simple integer approximation:

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int log2(unsigned int n) {

  int log = 0;

  if (n >= 1<<16) { n >>= 16; log += 16; }

  if (n >= 1<< 8) { n >>=  8; log +=  8; }

  if (n >= 1<< 4) { n >>=  4; log +=  4; }

  if (n >= 1<< 2) { n >>=  2; log +=  2; }

  if (n >= 1<< 1) {           log +=  1; }

  return ((n == 0) ? -1 : log);

}

(this assumes C or C++ being used).

kind regards,

Jos

dynamo

thanks for replying.really appreciate it

formula for logarithms to base two of a number

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re: formula for logarithms to base two of a number

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